scons: Enable -Wextra by default

Make best use of the compiler, and enable -Wextra as well as
-Wall. There are a few issues that had to be resolved, but they are
all trivial.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/dev/terminal.cc b/src/dev/terminal.cc
index e653ee115..6db43ef88 100644
--- a/src/dev/terminal.cc
+++ b/src/dev/terminal.cc
@@ -249,7 +249,7 @@ Terminal::read(uint8_t *buf, size_t len)
     if (data_fd < 0)
         panic("Terminal not properly attached.\n");
 
-    size_t ret;
+    ssize_t ret;
     do {
       ret = ::read(data_fd, buf, len);
     } while (ret == -1 && errno == EINTR);